The R38 class (also known as the A class) of rigid airships was designed for Britain's Royal Navy during the final months of World War I, intended for long-range patrol duties over the North Sea. Four such airships were originally ordered by the Admiralty, but orders for three of them (R39, R40 and R41) were cancelled after the armistice with Germany and work on the lead ship of the class, R38, continued only after the United States Navy had agreed to purchase her. At the time of her first flight in 1921, she was the world's largest airship.
The airship took off from Howden for her fourth test flight on 23 August 1921, which had an intended destination of RNAS Pulham, Norfolk where she could be moored to a mast, a facility lacking at Howden. In the event, mooring proved impossible because of low cloud and so the airship returned out to sea with the intention of running some high speed tests and then returning to Howden. The speed runs proved successful and as there was still daylight left it was decided to try some low altitude rudder tests to simulate the effects of the rough weather that could be expected on the Atlantic crossing.
At 17:37, fifteen degrees of rudder was applied over the city of Hull. Eye witnesses reported seeing creases down the envelope and then both ends drooped. This was followed by a fire in the bow and then a large explosion which broke windows over a large area. The airship had failed structurally and fell into the shallow waters of the Humber estuary. Sixteen of the 17 Americans and 28 of the 32 Britons in the crew were killed. The only American to survive was Rigger Norman C. Walker.The five who survived were in the tail section.
This disaster resulted in more deaths than the more famous Hindenburg disaster that killed 36. A memorial was erected at Hull, Yorkshire.